This invention relates to communications network management systems and more particularly to a protocol for improving the retrieval of specified items of information from network management systems and managed elements.
Protocols used by communications Network Management Systems (NMSs) for retrieving information from managed elements (MEs) or other NMSs commonly define a xe2x80x9cgetnextxe2x80x9d operation. The getnext operation is used in order to retrieve one or more items of information (called objects), when the NMS does not know beforehand how many objects exist, or even if any objects exist. The NMS typically sends repeated getnext commands to retrieve all objects contained in a series (such as all rows in a logical table), starting at the beginning of the series and continuing until either no more reply is received to the getnext command, or else a reply is received containing an object which lies outside of the desired series.
Similarly, a xe2x80x9cgetbulkxe2x80x9d command is typically defined, which allows an NMS to simultaneously retrieve all items in a series, by specifying (a) the object at the start of the desired series, and (b) the maximum number of successive objects to be retrieved.
The shortcoming of these approaches occurs when the same objects may be viewed as belonging to different series simultaneously. For example, a ME that is a packet switching device may have a table of cross connection objects. Within the table, there are types of cross connections, such as Permanent Virtual Circuits (PVCs), Switched Virtual Circuits (SVCs), and Soft Permanent Virtual Circuits (SPVCs). For the purposes of accounting for total utilization of the ME, the NMS may wish to retrieve information on all cross connections on the ME, regardless of type. For the purposes of allowing a user of the NMS to view and manage only particular types of cross connections (for example, only PVCs and SPVCs), the NMS may wish to retrieve information on these types but not on any other.
There are two prior art solutions to the problem of retrieving only selected objects from a series.
In the first prior art solution, the NMS retrieves all items in the series, and discards all those of a type which is not desired, before processing the information further. This has the major shortcoming that it is inefficient, from the point of view of:
a) processing resources on the ME (to copy information on each object into the xe2x80x9cgetxe2x80x9d reply);
b) processing resources on the NMS (to retrieve and examine each object from the reply); and
c) the amount of bandwidth utilized for communications between the ME and the NMS.
In the second prior art solution, different logical series of data are defined on the ME for the same information. For example, cross connections on a packet switch can be retrieved from an xe2x80x9call cross connectionsxe2x80x9d table, from a xe2x80x9cPVCxe2x80x9d table, from a xe2x80x9cSVCxe2x80x9d table, etc. The same objects would be accessible from different tables, depending on their type and the definition of the table. The NMS can therefore select whichever table is desired, to fulfill a particular management request. The shortcoming of this approach is that it is inflexible. The NMS cannot make xe2x80x9cad hocxe2x80x9d queries, that are for new or different types or combinations of types of objects within a series, unless the providers of the NMS and ME have previously agreed upon all types of series that will be supported.
It is an object of the present invention to provide an improved protocol for network management systems to retrieve objects from managed elements within the network or from other network managers.
Therefore in accordance with the present invention there is provided in a communications network management system in which items of information respecting managed elements within the network are retained within the managed elements, a protocol for improving retrieval of information from the managed elements, the improvement comprising adding one or more qualifiers to the items of information wherein the qualifiers represent subclasses of the information.